Benchmark: JavaScript spread operator vs Object.assign performance (same behaviour)

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject };
Using Object.assign
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = Object.assign({}, firstObject, secondObject);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using Object.assign

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.84 Safari/537.36

Browser/OS: Chrome 99 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Using the spread operator	1681848.4 Ops/sec
Using Object.assign	3052476.8 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months ago):

LLMs can make mistakes. Check important info.

**Understanding the Benchmark**

The provided benchmark compares the performance of two approaches to merge two objects: the spread operator (`...`) and `Object.assign()`. The goal is to determine which method is faster.

**Options Compared**

There are two options being compared:

1. **Using the spread operator**: This approach uses the spread operator (`...`) to create a new object with properties from both `firstObject` and `secondObject`.
2. **Using `Object.assign()`**: This approach uses the `Object.assign()` method to merge the properties of two objects into a new object.

**Pros and Cons of Each Approach**

1. **Using the spread operator**:
	* Pros:
		+ More concise and readable syntax.
		+ Faster performance, as it avoids creating intermediate objects.
	* Cons:
		+ Less intuitive for some developers who are not familiar with the spread operator.
2. **Using `Object.assign()`**:
	* Pros:
		+ More widely supported and understood by developers.
		+ Can be used to merge multiple objects into one.
	* Cons:
		+ Requires creating intermediate objects, which can lead to performance issues.

**Library Used: None**

There is no library being used in this benchmark. The tests are using native JavaScript features.

**Special JS Feature or Syntax: Spread Operator (`...`)**

The spread operator is a relatively new feature introduced in ECMAScript 2015 (ES6). It allows creating a new object with properties from an existing object, without explicitly specifying the keys. This syntax is more concise and readable than traditional ways of merging objects.

**Benchmark Preparation Code**

The preparation code for each test case is minimal:
```javascript
const firstObject = { sampleData: 'Hello world' };
const secondObject = { moreData: 'foo bar' };

// Using the spread operator
const finalObject = {
  ...firstObject,
  ...secondObject
};

// Using Object.assign()
const finalObjectAssign = Object.assign({}, firstObject, secondObject);
```
**Latest Benchmark Result**

The latest benchmark result shows that using the spread operator outperforms `Object.assign()` on this specific test case.

**Other Alternatives**

If you're looking for alternative approaches to merge objects, you can consider:

1. **Object.create()**: This method creates a new object with specified properties inherited from another object.
2. **Array.prototype.reduce()**: You can use the `reduce()` method to merge two objects into one.
3. **Library functions**: Depending on your specific requirements, you might need to use a library function like Lodash's `merge` or Underscore.js's `mergeObjects`.

Keep in mind that each approach has its pros and cons, and performance differences may vary depending on the specific use case and environment.

Related benchmarks:

JavaScript spread operator vs Object.assign performance (same behaviour) (version: 0)

Comparing performance of: Using the spread operator vs Using Object.assign

Created: 2 years ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months ago):